S. aureus, and all other Gram-positive bacteria studied except M.lysodeikticus, contain lipoteichoic acids. A study has been carried out to determine whether lipoteichoic acid antibodies are produced in humans during infection with S. aureus. We propose to continue to (1) identify immunologically active materials found in Streptococcus and Staphylococcus species; (2) to determine the biochemical steps involved in the synthesis of TA and LTA in S. aureus.